Second interview but still at other job?

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Okay, I had an interview today and I had called off work to go, and I had an interview and I felt I did great. She told me they might call for next week for a 2nd interview and I don't want to call off again, so I'm going to go to work half a day and tell my boss I have somewhere to go, but I don't want to tell him I'm going to an interview. What should I tell him? I love this job, but this other job pays way more. Thanks

Second interview but still at other job?